Baker's ammonia substitutes

A ready-mixed leavener containing an alkali, one or two acids and a starch buffer.

Best for

Spekulatius and thin spiced cookies, Springerle, shortbread-style German Christmas cookies, Lebkuchen with no honey or molasses, any recipe where you cannot buy hartshorn

Prep

Sift it in with the flour, and roll the dough a touch thinner than the original recipe specifies.

The reliable, everywhere-available answer, and the one to reach for if you are not going to think about it further. Understand the trade. Baking powder works by pairing an alkali with acids that react with it in the presence of moisture and heat, and the reaction leaves mineral salts in the dough. Those salts stay in the cookie, hold a little moisture, and slightly soften the bite, so a wafer that should shatter instead breaks with a faint bend. You also lose some spread: baker's ammonia gasses off early and hard, which is what makes thin doughs flow out wide and thin, whereas baking powder lifts more than it spreads, so your cookies come out a little taller, a little smaller across, and paler. Roll the dough slightly thinner than the recipe says and bake a minute or two longer at a slightly lower temperature to dry them out, and you will recover most of the crispness.

Pure alkali, which needs an acid in the dough to release its gas.

Best for

honey Lebkuchen and Pfefferkuchen, molasses and treacle cookies, gingerbread and Braune Kuchen, cocoa-containing doughs, recipes with sour cream, buttermilk or fruit juice

Prep

Dissolve it in a teaspoon of the recipe's liquid so it disperses evenly and does not leave bitter pockets.

This is the better choice than baking powder whenever the recipe already has something sour in it, which in German Christmas baking it very often does, because honey, molasses, dark brown sugar and cocoa are all mildly acidic. Baking soda gives you the wide, generous spread that baker's ammonia gives, and because it leaves the dough alkaline it browns hard, which is exactly the deep mahogany colour a good Lebkuchen wants. The risks are specific. Too much tastes soapy and faintly metallic, so measure carefully and start with half the volume of the ammonia called for. And in a pale dough with no acid at all, such as a plain Springerle, baking soda has nothing to react with, so it will simply sit there tasting bitter. Reserve it for dark, sweet, spiced doughs.

The other traditional German leavener, sold beside hartshorn in German supermarkets at Christmas.

Best for

honey Lebkuchen, Pfefferkuchen and Printen, Elisenlebkuchen, traditional recipes that already call for both potash and hartshorn

Prep

Dissolve in a teaspoon or two of cold water and stir into the wet ingredients.

If you are baking from a German recipe, this is the ingredient most likely to be sitting right next to the hartshorn on the shelf, and traditional Lebkuchen recipes often use both because they do different jobs: potash gives lift and deep browning, hartshorn gives spread and crispness. Used alone in place of hartshorn, potash browns beautifully and lifts well, but it leaves potassium salts in the crumb, so the cookie is softer and slightly chewy rather than brittle, and it can taste faintly soapy and mineral if you overdo it. It also needs an acidic dough to work properly, so it belongs in honey and molasses doughs and not in pale ones. Always dissolve it in a spoonful of water before mixing it in; added dry it clumps and leaves bitter spots.

A hybrid that borrows spread and browning from the soda and reliability from the powder.

Best for

thin Spekulatius, spiced Christmas cookies, cut-out cookies that should stay flat, Lebkuchen

Prep

Sift both with the flour; do not increase the soda hoping for more browning.

This is the most useful compromise for anyone who wants the cookie to look right as well as taste right. The small amount of baking soda pushes the dough slightly alkaline, which encourages both the spread and the browning that baker's ammonia produces, while the baking powder guarantees enough lift so nothing comes out dense. Expect a cookie that is very close in appearance and about ninety per cent of the way there on snap. The remaining difference is unavoidable: the residues left behind keep it very slightly softer, and it will not stay crisp for as many weeks in the tin.

No chemical leavening at all, relying on beaten egg and long drying for structure.

Best for

Springerle and other moulded picture cookies, very thin wafer cookies, any cookie whose whole point is holding a stamped pattern

Prep

Let stamped cookies air-dry uncovered for eight to twenty-four hours before baking so the pattern sets.

Worth taking seriously, and for one type of cookie it is arguably the best answer available. A moulded cookie such as Springerle or a carved Model cookie is stamped with a design and then left uncovered to dry for many hours before baking, and its structure comes mainly from long-beaten egg and sugar. Adding a leavener that puffs enthusiastically is what blurs the pattern. Omitting it altogether gives you a hard, dense, very crisp cookie that holds every detail of the mould, which is what those cookies traditionally were and why they keep for months. The honest downsides: it is harder and more tooth-testing, so it is meant to be eaten with coffee or after a few days of softening in a tin with an apple slice, and it will not work for any cookie that is supposed to rise, such as a soft Lebkuchen. Do not omit the leavener from a dough that is supposed to spread and puff.